Chilled Water Pipe

[robinxie]

Can anyone tell me the means how to overcome the contraction of chilled water pipe in the piping design? I have about 1000ft STRAIGHT pipe ( I can not have the L loop or U loop within it), the contraction is about 2". I know I can have expansion joint or cold spring to overcome expansion for the steam pipe. But how can I do for the chilled water pipe?
Any information and any reference will be appreciated.


Robin

 

[quark]

robinxie!

You can use stainless steel flexible bellows for this application. They come in flanged ends and simply you have to install in your pipe line.

Regards,

 

[robinxie]

Many thanks, quark.
Could you please tell me some manufacturers of this kind of stainless bellows?

Robin

 

[butelja]

One of the major bellows manufacturers is Pathway Bellows / Sr. Flexonics. I'm sure there are many others, but they are probably the biggest in the USA. A word of caution is in order. If you use a bellows, you must also consider the pressure thrust that must be absorbed by proper guides and anchors. For chilled water, an elastomer (rubber) expansion joint may be adequate, and certainly less expensive than metal bellows.

Of course, you can install expansion bends or loops just as would be done in a hot line. While more expensive, it creates a more robust system. Whether it is justified for chilled water is questionable.

 

[KernOily]

There are several ways to fix this. In lieu of the metal bellows-type expansion joint, you can use a rubber hose covered with a stainless steel braid to accept the contraction. You might have to use more than one to accept the full 2" contraction. Another one is a small prefabricated expansion loop. Metraflex is the company that makes these devices. If the system is low pressure, e.g. not exceeding a couple hundred psig, you can use one or more rubber bellows expansion joints made by e.g. Garlock.

You can also still use cold spring; it's just a matter of proper design. If you do that make sure you address the reaction forces set up on the equipment flanges, or whatever your end connections are, after the system reaches operating temperature. Thanks!
Pete
pjchandl@prou.com

 

[butelja]

I second all of Pete's recommendations, except for the braided hose in compression. If you compress a hose that has an overbraid, the inner liner can buckle. In a metal hose, this can cause catastrophic failure. I'm not sure about a rubber liner, but it has the potential to be a significant flow restriction if it buckles.

Upon reflection, the Metraflex is probably the best solution, providing there are no plant rules or specifications preventing it's use, and the chilled water pipes are not very large diameter. There is no pressure thrust generated, and there is no hose in compression problems.